Palynoflora from Deccan volcano-sedimentary sequence (Cretaceous-Palaeogene transition) of central India: implications for spatio-temporal correlation

Abstract

The sedimentary beds associated with Deccan Continental Flood Basalt (DCFB) sequences exposed in the volcanic subprovinces of Jabalpur-Mandla-Chhindwara (JMC) regions of Madhya Pradesh and Nand-Dongargaon (N-D) basin and the adjoining areas to the west in Yeotmal-Nanded in Maharashtra were studied for their palynofloral analysis. The sediments were characterized palynologically and changes in the palynoflora are observed at different stratigraphic levels in a number of sections including several new intertrappean localities recorded in recent years. For the purpose of effective correlation of different subprovinces, palynofloras of some of the previously studied intertrappeans are also reviewed. Our studies suggest that before the start of the Deccan volcanic activity, the palynoflora found in the Lameta sediments, was dominated by gymnosperms-angiosperm association. The plant canopy consisted mainly of gymnosperms (Conifers and Podocarpaceae) whereas, the understory members were mostly of palms and herbs (Poaceae and Asteraceae). The eruption of Deccan volcanic flows severely affected the existing floral association and proved fatal for the well established plant community. The immediately overlying sediments associated with the earliest volcanic flows are dominated by pteridophytes and angiosperm taxa (Azolla cretacea, Aquilapollenites bengalensis, Ariadnaesporites sp., Gabonisporis vigourouxii and Triporoletes reticulatus). Higher up in the stratigraphic sequence, similar forms continued with simultaneous appearance of new taxa including Scabrastephanocolpites spp. At still higher stratigraphic levels, abundance of fungi especially the mycorrhizal fungi, concurrent with sharp decline in pollen/spore recovery was observed. In the culminating phase (i.e. Palaeocene) of Deccan volcanic history a new palynofloral assemblage of typical Palaeocene taxa (Dandotiaspora dilata, D. pseudoauriculata, D. plicata, Spinizonocolpites echinatus, Matanomadhiasulcites sp., and Lakiapollis ovatus) was encountered.